Generic Formatter code

[Bert Wesarg]

Hello,

I see on the newly created/imported feature whichlist these two points:

 * Make stats line configurable, possibly using a printf()-like string.
 * The icon title should be configurable.

What is missing for this is a similar implementation as for the window
title, so I hacked a proof-of-concept for a generic one, that have similar
features that are needed for the GUI building of these formatting strings.

And a little more:

 * full flag character support (#0- +)
 * full width and precision support (\d+.\d+)
 * long format names: like %(filename) or %{host}
 * pattern matching for these long names, e.g. in the format something
   like this: %(HOME) and a rule "*" that look in the envirionment for
  "HOME"

There is somethings missing:
 * no removing of surrounding spaces/braces
 * no surrounding braces with appending
 * ...

file is attached (I hope), if not it can also downloaded here:

https://nirvana.informatik.uni-halle.de/~wesarg/test_format.c

I'm open for comments/suggestions/...

Regards
Bert